namespace feng3d
{

    /**
     * Ported from Stefan Gustavson's java implementation
     * http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
     * Read Stefan's excellent paper for details on how this code works.
     * 
     * Sean McCullough banksean@gmail.com
     * 
     * Added 4D noise
     * Joshua Koo zz85nus@gmail.com
     * 
     * @see https://github.com/mrdoob/three.js/blob/dev/examples/js/math/SimplexNoise.js
     */
    export class SimplexNoise
    {
        private _p: number[];
        private _perm: number[];

        /**
         * You can pass in a random number generator object if you like.
         * It is assumed to have a random() method.
         */
        constructor(r?: { random: () => number })
        {
            if (r == undefined) r = Math;

            this._p = [];
            for (var i = 0; i < 256; i++)
            {
                this._p[i] = Math.floor(r.random() * 256);
            }
            // To remove the need for index wrapping, double the permutation table length
            this._perm = [];
            for (var i = 0; i < 512; i++)
            {
                this._perm[i] = this._p[i & 255];
            }
        }

        /**
         * 
         * @param xin 
         * @param yin 
         */
        noise(xin: number, yin: number)
        {
            var n0: number, n1: number, n2: number; // Noise contributions from the three corners
            // Skew the input space to determine which simplex cell we're in
            var F2 = 0.5 * (Math.sqrt(3.0) - 1.0);
            var s = (xin + yin) * F2; // Hairy factor for 2D
            var i = Math.floor(xin + s);
            var j = Math.floor(yin + s);
            var G2 = (3.0 - Math.sqrt(3.0)) / 6.0;
            var t = (i + j) * G2;
            var X0 = i - t; // Unskew the cell origin back to (x,y) space
            var Y0 = j - t;
            var x0 = xin - X0; // The x,y distances from the cell origin
            var y0 = yin - Y0;
            // For the 2D case, the simplex shape is an equilateral triangle.
            // Determine which simplex we are in.
            var i1: number, j1: number; // Offsets for second (middle) corner of simplex in (i,j) coords
            if (x0 > y0)
            {
                i1 = 1; j1 = 0;
                // lower triangle, XY order: (0,0)->(1,0)->(1,1)
            } else
            {
                i1 = 0; j1 = 1;
            }
            // upper triangle, YX order: (0,0)->(0,1)->(1,1)
            // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
            // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
            // c = (3-sqrt(3))/6
            var x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
            var y1 = y0 - j1 + G2;
            var x2 = x0 - 1.0 + 2.0 * G2; // Offsets for last corner in (x,y) unskewed coords
            var y2 = y0 - 1.0 + 2.0 * G2;
            // Work out the hashed gradient indices of the three simplex corners
            var ii = i & 255;
            var jj = j & 255;
            var gi0 = this._perm[ii + this._perm[jj]] % 12;
            var gi1 = this._perm[ii + i1 + this._perm[jj + j1]] % 12;
            var gi2 = this._perm[ii + 1 + this._perm[jj + 1]] % 12;
            // Calculate the contribution from the three corners
            var t0 = 0.5 - x0 * x0 - y0 * y0;
            if (t0 < 0) n0 = 0.0;
            else
            {
                t0 *= t0;
                n0 = t0 * t0 * _dot(_grad3[gi0], x0, y0); // (x,y) of grad3 used for 2D gradient
            }
            var t1 = 0.5 - x1 * x1 - y1 * y1;
            if (t1 < 0) n1 = 0.0;
            else
            {
                t1 *= t1;
                n1 = t1 * t1 * _dot(_grad3[gi1], x1, y1);
            }
            var t2 = 0.5 - x2 * x2 - y2 * y2;
            if (t2 < 0) n2 = 0.0;
            else
            {
                t2 *= t2;
                n2 = t2 * t2 * _dot(_grad3[gi2], x2, y2);
            }
            // Add contributions from each corner to get the final noise value.
            // The result is scaled to return values in the interval [-1,1].
            return 70.0 * (n0 + n1 + n2);
        }

        /**
         * 3D simplex noise
         * 
         * @param xin 
         * @param yin 
         * @param zin 
         */
        noise3d(xin: number, yin: number, zin: number)
        {
            var n0: number, n1: number, n2: number, n3: number; // Noise contributions from the four corners
            // Skew the input space to determine which simplex cell we're in
            var F3 = 1.0 / 3.0;
            var s = (xin + yin + zin) * F3; // Very nice and simple skew factor for 3D
            var i = Math.floor(xin + s);
            var j = Math.floor(yin + s);
            var k = Math.floor(zin + s);
            var G3 = 1.0 / 6.0; // Very nice and simple unskew factor, too
            var t = (i + j + k) * G3;
            var X0 = i - t; // Unskew the cell origin back to (x,y,z) space
            var Y0 = j - t;
            var Z0 = k - t;
            var x0 = xin - X0; // The x,y,z distances from the cell origin
            var y0 = yin - Y0;
            var z0 = zin - Z0;
            // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
            // Determine which simplex we are in.
            var i1: number, j1: number, k1: number; // Offsets for second corner of simplex in (i,j,k) coords
            var i2: number, j2: number, k2: number; // Offsets for third corner of simplex in (i,j,k) coords
            if (x0 >= y0)
            {
                if (y0 >= z0)
                {
                    i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
                    // X Y Z order
                } else if (x0 >= z0)
                {
                    i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1;
                    // X Z Y order
                } else
                {
                    i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1;
                } // Z X Y order
            } else
            { // x0<y0

                if (y0 < z0)
                {
                    i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1;
                    // Z Y X order
                } else if (x0 < z0)
                {
                    i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1;
                    // Y Z X order
                } else
                {
                    i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
                } // Y X Z order
            }
            // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
            // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
            // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
            // c = 1/6.
            var x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
            var y1 = y0 - j1 + G3;
            var z1 = z0 - k1 + G3;
            var x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords
            var y2 = y0 - j2 + 2.0 * G3;
            var z2 = z0 - k2 + 2.0 * G3;
            var x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords
            var y3 = y0 - 1.0 + 3.0 * G3;
            var z3 = z0 - 1.0 + 3.0 * G3;
            // Work out the hashed gradient indices of the four simplex corners
            var ii = i & 255;
            var jj = j & 255;
            var kk = k & 255;
            var gi0 = this._perm[ii + this._perm[jj + this._perm[kk]]] % 12;
            var gi1 = this._perm[ii + i1 + this._perm[jj + j1 + this._perm[kk + k1]]] % 12;
            var gi2 = this._perm[ii + i2 + this._perm[jj + j2 + this._perm[kk + k2]]] % 12;
            var gi3 = this._perm[ii + 1 + this._perm[jj + 1 + this._perm[kk + 1]]] % 12;
            // Calculate the contribution from the four corners
            var t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
            if (t0 < 0) n0 = 0.0;
            else
            {
                t0 *= t0;
                n0 = t0 * t0 * _dot3(_grad3[gi0], x0, y0, z0);
            }
            var t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
            if (t1 < 0) n1 = 0.0;
            else
            {
                t1 *= t1;
                n1 = t1 * t1 * _dot3(_grad3[gi1], x1, y1, z1);
            }
            var t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
            if (t2 < 0) n2 = 0.0;
            else
            {
                t2 *= t2;
                n2 = t2 * t2 * _dot3(_grad3[gi2], x2, y2, z2);
            }
            var t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
            if (t3 < 0) n3 = 0.0;
            else
            {
                t3 *= t3;
                n3 = t3 * t3 * _dot3(_grad3[gi3], x3, y3, z3);
            }
            // Add contributions from each corner to get the final noise value.
            // The result is scaled to stay just inside [-1,1]
            return 32.0 * (n0 + n1 + n2 + n3);
        }

        /**
         * 4D simplex noise
         * 
         * @param x 
         * @param y 
         * @param z 
         * @param w 
         */
        noise4d(x: number, y: number, z: number, w: number)
        {
            // For faster and easier lookups
            var grad4 = _grad4;
            var simplex = _simplex;
            var perm = this._perm;

            // The skewing and unskewing factors are hairy again for the 4D case
            var F4 = (Math.sqrt(5.0) - 1.0) / 4.0;
            var G4 = (5.0 - Math.sqrt(5.0)) / 20.0;
            var n0, n1, n2, n3, n4; // Noise contributions from the five corners
            // Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
            var s = (x + y + z + w) * F4; // Factor for 4D skewing
            var i = Math.floor(x + s);
            var j = Math.floor(y + s);
            var k = Math.floor(z + s);
            var l = Math.floor(w + s);
            var t = (i + j + k + l) * G4; // Factor for 4D unskewing
            var X0 = i - t; // Unskew the cell origin back to (x,y,z,w) space
            var Y0 = j - t;
            var Z0 = k - t;
            var W0 = l - t;
            var x0 = x - X0; // The x,y,z,w distances from the cell origin
            var y0 = y - Y0;
            var z0 = z - Z0;
            var w0 = w - W0;

            // For the 4D case, the simplex is a 4D shape I won't even try to describe.
            // To find out which of the 24 possible simplices we're in, we need to
            // determine the magnitude ordering of x0, y0, z0 and w0.
            // The method below is a good way of finding the ordering of x,y,z,w and
            // then find the correct traversal order for the simplex we’re in.
            // First, six pair-wise comparisons are performed between each possible pair
            // of the four coordinates, and the results are used to add up binary bits
            // for an integer index.
            var c1 = (x0 > y0) ? 32 : 0;
            var c2 = (x0 > z0) ? 16 : 0;
            var c3 = (y0 > z0) ? 8 : 0;
            var c4 = (x0 > w0) ? 4 : 0;
            var c5 = (y0 > w0) ? 2 : 0;
            var c6 = (z0 > w0) ? 1 : 0;
            var c = c1 + c2 + c3 + c4 + c5 + c6;
            var i1: number, j1: number, k1: number, l1: number; // The integer offsets for the second simplex corner
            var i2: number, j2: number, k2: number, l2: number; // The integer offsets for the third simplex corner
            var i3: number, j3: number, k3: number, l3: number; // The integer offsets for the fourth simplex corner
            // simplex[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order.
            // Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w
            // impossible. Only the 24 indices which have non-zero entries make any sense.
            // We use a thresholding to set the coordinates in turn from the largest magnitude.
            // The number 3 in the "simplex" array is at the position of the largest coordinate.
            i1 = simplex[c][0] >= 3 ? 1 : 0;
            j1 = simplex[c][1] >= 3 ? 1 : 0;
            k1 = simplex[c][2] >= 3 ? 1 : 0;
            l1 = simplex[c][3] >= 3 ? 1 : 0;
            // The number 2 in the "simplex" array is at the second largest coordinate.
            i2 = simplex[c][0] >= 2 ? 1 : 0;
            j2 = simplex[c][1] >= 2 ? 1 : 0; k2 = simplex[c][2] >= 2 ? 1 : 0;
            l2 = simplex[c][3] >= 2 ? 1 : 0;
            // The number 1 in the "simplex" array is at the second smallest coordinate.
            i3 = simplex[c][0] >= 1 ? 1 : 0;
            j3 = simplex[c][1] >= 1 ? 1 : 0;
            k3 = simplex[c][2] >= 1 ? 1 : 0;
            l3 = simplex[c][3] >= 1 ? 1 : 0;
            // The fifth corner has all coordinate offsets = 1, so no need to look that up.
            var x1 = x0 - i1 + G4; // Offsets for second corner in (x,y,z,w) coords
            var y1 = y0 - j1 + G4;
            var z1 = z0 - k1 + G4;
            var w1 = w0 - l1 + G4;
            var x2 = x0 - i2 + 2.0 * G4; // Offsets for third corner in (x,y,z,w) coords
            var y2 = y0 - j2 + 2.0 * G4;
            var z2 = z0 - k2 + 2.0 * G4;
            var w2 = w0 - l2 + 2.0 * G4;
            var x3 = x0 - i3 + 3.0 * G4; // Offsets for fourth corner in (x,y,z,w) coords
            var y3 = y0 - j3 + 3.0 * G4;
            var z3 = z0 - k3 + 3.0 * G4;
            var w3 = w0 - l3 + 3.0 * G4;
            var x4 = x0 - 1.0 + 4.0 * G4; // Offsets for last corner in (x,y,z,w) coords
            var y4 = y0 - 1.0 + 4.0 * G4;
            var z4 = z0 - 1.0 + 4.0 * G4;
            var w4 = w0 - 1.0 + 4.0 * G4;
            // Work out the hashed gradient indices of the five simplex corners
            var ii = i & 255;
            var jj = j & 255;
            var kk = k & 255;
            var ll = l & 255;
            var gi0 = perm[ii + perm[jj + perm[kk + perm[ll]]]] % 32;
            var gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1 + perm[ll + l1]]]] % 32;
            var gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2 + perm[ll + l2]]]] % 32;
            var gi3 = perm[ii + i3 + perm[jj + j3 + perm[kk + k3 + perm[ll + l3]]]] % 32;
            var gi4 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1 + perm[ll + 1]]]] % 32;
            // Calculate the contribution from the five corners
            var t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0;
            if (t0 < 0) n0 = 0.0;
            else
            {
                t0 *= t0;
                n0 = t0 * t0 * _dot4(grad4[gi0], x0, y0, z0, w0);
            }
            var t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1 - w1 * w1;
            if (t1 < 0) n1 = 0.0;
            else
            {
                t1 *= t1;
                n1 = t1 * t1 * _dot4(grad4[gi1], x1, y1, z1, w1);
            }
            var t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2 - w2 * w2;
            if (t2 < 0) n2 = 0.0;
            else
            {
                t2 *= t2;
                n2 = t2 * t2 * _dot4(grad4[gi2], x2, y2, z2, w2);
            }
            var t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3 - w3 * w3;
            if (t3 < 0) n3 = 0.0;
            else
            {
                t3 *= t3;
                n3 = t3 * t3 * _dot4(grad4[gi3], x3, y3, z3, w3);
            }
            var t4 = 0.6 - x4 * x4 - y4 * y4 - z4 * z4 - w4 * w4;
            if (t4 < 0) n4 = 0.0;
            else
            {
                t4 *= t4;
                n4 = t4 * t4 * _dot4(grad4[gi4], x4, y4, z4, w4);
            }
            // Sum up and scale the result to cover the range [-1,1]
            return 27.0 * (n0 + n1 + n2 + n3 + n4);
        }
    }

    var _grad3 = [[1, 1, 0], [- 1, 1, 0], [1, - 1, 0], [- 1, - 1, 0],
    [1, 0, 1], [- 1, 0, 1], [1, 0, - 1], [- 1, 0, - 1],
    [0, 1, 1], [0, - 1, 1], [0, 1, - 1], [0, - 1, - 1]];

    var _grad4 = [[0, 1, 1, 1], [0, 1, 1, - 1], [0, 1, - 1, 1], [0, 1, - 1, - 1],
    [0, - 1, 1, 1], [0, - 1, 1, - 1], [0, - 1, - 1, 1], [0, - 1, - 1, - 1],
    [1, 0, 1, 1], [1, 0, 1, - 1], [1, 0, - 1, 1], [1, 0, - 1, - 1],
    [- 1, 0, 1, 1], [- 1, 0, 1, - 1], [- 1, 0, - 1, 1], [- 1, 0, - 1, - 1],
    [1, 1, 0, 1], [1, 1, 0, - 1], [1, - 1, 0, 1], [1, - 1, 0, - 1],
    [- 1, 1, 0, 1], [- 1, 1, 0, - 1], [- 1, - 1, 0, 1], [- 1, - 1, 0, - 1],
    [1, 1, 1, 0], [1, 1, - 1, 0], [1, - 1, 1, 0], [1, - 1, - 1, 0],
    [- 1, 1, 1, 0], [- 1, 1, - 1, 0], [- 1, - 1, 1, 0], [- 1, - 1, - 1, 0]];

    // A lookup table to traverse the simplex around a given point in 4D.
    // Details can be found where this table is used, in the 4D noise method.
    var _simplex = [
        [0, 1, 2, 3], [0, 1, 3, 2], [0, 0, 0, 0], [0, 2, 3, 1], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [1, 2, 3, 0],
        [0, 2, 1, 3], [0, 0, 0, 0], [0, 3, 1, 2], [0, 3, 2, 1], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [1, 3, 2, 0],
        [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0],
        [1, 2, 0, 3], [0, 0, 0, 0], [1, 3, 0, 2], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [2, 3, 0, 1], [2, 3, 1, 0],
        [1, 0, 2, 3], [1, 0, 3, 2], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [2, 0, 3, 1], [0, 0, 0, 0], [2, 1, 3, 0],
        [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0],
        [2, 0, 1, 3], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [3, 0, 1, 2], [3, 0, 2, 1], [0, 0, 0, 0], [3, 1, 2, 0],
        [2, 1, 0, 3], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [3, 1, 0, 2], [0, 0, 0, 0], [3, 2, 0, 1], [3, 2, 1, 0]];

    function _dot(g: number[], x: number, y: number)
    {
        return g[0] * x + g[1] * y;
    }

    function _dot3(g: number[], x: number, y: number, z: number)
    {
        return g[0] * x + g[1] * y + g[2] * z;
    }

    function _dot4(g: number[], x: number, y: number, z: number, w: number)
    {
        return g[0] * x + g[1] * y + g[2] * z + g[3] * w;
    }
}